Rotary wing aircraft, such as helicopters, provide unique environments for the use of ball bearings, particularly in their rotor systems. For example, the bearings in helicopter swashplates and in rotor blade mounts must be specially designed to provide reliable ongoing use under the type of load and speed conditions that are unique to helicopters. The use of bearings in other types of machines is nonanalogous to rotary wing aircraft bearings in general and to helicopter bearings in particular. For this reason, bearing designs that are useful in other kinds of machines are not assumed by those of ordinary skill in the art to be suitable for helicopter swashplates, rotor blade mounts, etc.
One example of a conventional rotary wing aircraft bearing is in the tail rotor blade mount of a Sikorsky CH53A/D helicopter. The blade mount includes a 5-bearing stack of ball bearings in which the balls are held in place by a nylon cage. To accommodate the cage, the outer rings of the bearings must be chamfered, which weakens the bearings.